(1) Field of the Invention
The present invention relates to devices and methods for measuring and testing, and more particularly, to devices and methods for measuring forces and force components.
(2) Description of the Prior Art
Existing force measuring devices, force balance and load cells, are complex and expensive systems. Although custom load cells can be fabricated to suit most load measuring requirements, once they have been constructed, their force measurement range and sensitivity are fixed. At the present time, there are no load measurement systems available that can be configured to suit a particular load-measuring requirement without rebuilding the device.
U.S. Pat. No. 4,094,192 to Watson et al., for example, discloses a six-degree force sensor in which top and bottom sections are coupled to one another by connecting sections. Strain gauges are affixed to these connecting sections.
U.S. Pat. No. 4,161,874 to Specker et al. discloses a force measuring system in which a plate is supported by a plurality of load cell assemblies. Clevis members pivotally mount each of these load cell assemblies at either end.
U.S. Pat. No. 4,196,337 to Jewett et al. discloses a torque sensor in which cylindrical rings are spaced apart from one another by elongated beams. Each of these beams has strain gauges mounted thereto.
U.S. Pat. No. 4,550,617 to Fratgner, et al. discloses a multi-axis force and member transducer, which has a plurality of flexible plates that are orthogonally oriented and interconnected between first and second bodies to measure the forces exerted thereon due to relative movement between the bodies. The interconnection between a first element attached to the first body and a second element attached to the second body is affected by a plurality of first thin flexible plates and a plurality of second thin flexible plates, the ends of the plates being interconnected by a ball-joint coupling. The first thin flexible plates are oriented such that they flex in a direction generally perpendicular to a first axis, while the second thin flexible plates are oriented such that they flex in a direction generally parallel to such axis. Strain gauges may be provided on each of the thin flexible plates to provide an output of the forces.
U.S. Pat. No. 4,745,565 to Garwin et al. discloses a force sensing type data input device in which two parallel space plates are separated from one another by a plurality of force sensors.
U.S. Pat. No. 5,063,788 to Ch'Hayder et al. discloses a sensor for measuring three components of force and three components of moment. The sensor is comprised of one unitary mechanical piece comprising two end faces by which may be secured respectively to a body generating force. A central portion comprising six beams with means for measuring deformation are arranged according to a closed triangular architecture between the two end faces.
U.S. Pat. No. 5,339,697 to Mullin discloses an assembly which measures force along and moments about three orthogonal axes and which reports low cross talk. The structure includes a load cell in which a plurality of links connects couple plates to one another to allow for six degrees of freedom.
A need, however, continues to exist for a force measurement device that can be configured for a particular loading range without fabricating new load sensing elements.